Rancho La Brea

Mammals at Rancho La Brea

Approximately 90% of the mammals excavated at Rancho La Brea are carnivores. This proportion is due to the nature of the asphalt seeps that form a carnivore trap. When a large herbivore became mired in the asphalt, it attracted predators and scavengers to the site and these in turn became trapped. Large carnivores are represented by the dog family (Canidae), the cat family (Felidae) and the bear family (Ursidae). The most common large carnivore is the dire wolf (Canis dirus). Small carnivores include weasels, badgers, and skunks (Mustelidae), the elusive ringtail and raccoon (Procyonidae). Other groups of animals include shrews, moles, bats, giant ground sloths, rabbits, rodents, mastodons, mammoths, horses, tapirs, peccaries, camels, deer, pronghorns, and bison. The ancient bison (Bison antiquus) is the most common large herbivore and is represented by at least 300 individuals, many of them young.

Canidae

Five species from the dog family are presently known from Rancho La Brea. The extinct dire wolf (Canis dirus), represented by over 200,000 specimens (~ 4,000+ individuals), is by far the most common large animal recovered. Dire wolves were widespread throughout North America during the Pleistocene and their remains have been found at many fossil localities. It appears that the Californian specimens were slightly smaller than the ones in the central and eastern United States. The timber wolf (C. lupus), coyote (C. latrans), domestic dog (C. familiaris), and the gray fox (Urocyon cinereoargenteus) are still living today although the timber wolf no longer lives in Southern California.

Felidae

Six species of the cat family are known from Rancho La Brea. They comprise two main groups, the machairodonts (saber-toothed cats) and the true cats. The extinct saber-toothed cat (Smilodon fatalis) is probably the most well known and is California's state fossil. At least 2,000 individuals of Smilodon are represented by over 130,000 specimens. The distantly related scimitar cat (Homotherium serum) is very rare and known only from a few teeth and several metapodials. The American lion (Panthera atrox) is the most common of the true cats with about 80 individuals recovered, two-thirds of which are males. Other cats include the puma (Felis concolor), the lynx (F. rufus), the jaguar (F. onca), and a domestic cat. It is possible that the American cheetah (Miracinonyx inexpectatus) was also in the area at the end of the Pleistocene although no specimen has yet been identified from Rancho La Brea.

Ursidae

Three species of bear are known from Rancho La Brea. The extinct giant short-faced bear (Arctodus simus), represented by 30 plus individuals, is both the largest and most common species recovered. Thus far, at least 700 elements have been identified. The short-faced bear had an extensive North American distribution ranging from the Yukon to Texas. Its closest living relative is the spectacled bear that lives in the Andes. Possibly the largest predator of the Ice Age, the male short-faced bear may have weighed up to 1,800 pounds and stood five feet at the shoulder. Sexual dimorphism is very evident with females being at least 25 percent smaller than the males. The black bear (Ursus americanus) and the grizzly bear (U. arctos) are restricted to the younger deposits and are rare.